Electronic systems that “push” (i.e. automatically transmit) electronic mail (“e-mail”) messages to wireless communication devices are well-known. In an exemplary system, an intermediary server monitors an “inbox” (typically, a folder or other store where incoming messages are stored) of an e-mail account at an e-mail server. When an e-mail message arrives at the monitored inbox, the intermediary server “pushes” the e-mail message to the wireless communication device (also referred to herein as a “mobile device”) by way of a data network (such as the public Internet) and a wireless network. If the e-mail message has an attachment (i.e. a computer file that accompanies the e-mail message, such as a word processing file, image file or spreadsheet, for example), the intermediary server may refrain from automatically pushing the attachment to the device, and may instead await a user request for the attachment from the wireless communication device before transmitting some or all of the attachment to the device.
When an e-mail message having an attachment is pushed to the wireless communication device without the attachment, the fact that the message has an associated attachment may be indicated to the user by, for example, an icon displayed in association with the message. The appearance of the icon may also indicate the nature of the attachment (e.g. word processing file, image file, spreadsheet, etc.). If the user opts to view the attachment, by selecting the icon for example, a request for a first portion of the attachment may be automatically generated and transmitted via the wireless network to the intermediary server. The attachment service at the intermediary server may reformat the attachment for display on a small device screen or paginate the attachment to support piecemeal downloading of portions (“chunks”) of the attachment as the user pages or otherwise scrolls up and down through the attachment using the attachment viewer. The attachment service may then transmit the first “chunk” of the attachment to the device. A chunk may, for example, be a two kilobyte (2 KB) portion of the processed attachment. The chunk may be displayed by the attachment viewer along with a “more” menu item. Selection of the “more” menu item may cause a request for another chunk to be sent to the intermediary server.
At any given time, the wireless communication device may store, in its local memory, numerous e-mail messages that have been “pushed” to the device. For e-mail messages having at least one attachment, the attachment may be resident in memory at the wireless communication device in whole, in part (e.g. in the form of one or more chunks), or not at all, depending upon whether or not it has been transmitted to the device, responsive to the user's interactions with the attachment viewer.